[PATCH v2 1/4] KVM: x86: hyperv: Remove duplicate definitions of Reference TSC Page

From: Michael Kelley
Date: Wed Apr 22 2020 - 15:58:45 EST


The Hyper-V Reference TSC Page structure is defined twice. struct
ms_hyperv_tsc_page has padding out to a full 4 Kbyte page size. But
the padding is not needed because the declaration includes a union
with HV_HYP_PAGE_SIZE. KVM uses the second definition, which is
struct _HV_REFERENCE_TSC_PAGE, because it does not have the padding.

Fix the duplication by removing the padding from ms_hyperv_tsc_page.
Fix up the KVM code to use it. Remove the no longer used struct
_HV_REFERENCE_TSC_PAGE.

There is no functional change.

Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/include/asm/hyperv-tlfs.h | 8 --------
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/hyperv.c | 4 ++--
3 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 29336574d0bc..0e4d76920957 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -303,7 +303,6 @@ struct ms_hyperv_tsc_page {
u32 reserved1;
volatile u64 tsc_scale;
volatile s64 tsc_offset;
- u64 reserved2[509];
} __packed;

/*
@@ -433,13 +432,6 @@ enum HV_GENERIC_SET_FORMAT {
*/
#define HV_CLOCK_HZ (NSEC_PER_SEC/100)

-typedef struct _HV_REFERENCE_TSC_PAGE {
- __u32 tsc_sequence;
- __u32 res1;
- __u64 tsc_scale;
- __s64 tsc_offset;
-} __packed HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
-
/* Define the number of synthetic interrupt sources. */
#define HV_SYNIC_SINT_COUNT (16)
/* Define the expected SynIC version. */
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 42a2d0d3984a..4698343b9a05 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -865,7 +865,7 @@ struct kvm_hv {
u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
u64 hv_crash_ctl;

- HV_REFERENCE_TSC_PAGE tsc_ref;
+ struct ms_hyperv_tsc_page tsc_ref;

struct idr conn_to_evt;

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bcefa9d4e57e..1f3c6fd3cdaa 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -900,7 +900,7 @@ static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
* These two equivalencies are implemented in this function.
*/
static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info *hv_clock,
- HV_REFERENCE_TSC_PAGE *tsc_ref)
+ struct ms_hyperv_tsc_page *tsc_ref)
{
u64 max_mul;

@@ -941,7 +941,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
u64 gfn;

BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
- BUILD_BUG_ON(offsetof(HV_REFERENCE_TSC_PAGE, tsc_sequence) != 0);
+ BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);

if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
return;
--
2.18.2